1. Field of the Invention
The present invention relates to a joint between a fiber reinforced resin and a metal.
2. Description of the Related Art
Fiber reinforced plastics (FRPs) are today used widely in structural members for aircraft, vehicles, ships, and general industrial instruments. For example, a known structural member is formed by impregnating a woven fabric, which is constituted by inorganic reinforcing fibers such as carbon fibers or glass fibers that are disposed in crisscross arrangement and interwoven, with a resin such as epoxy resin, and then hardening the resin.
In many cases, however, structural members are not formed entirely from fiber reinforced plastics, and a metallic material must be applied partially thereto.
It is therefore necessary to join the fiber reinforced plastic and the metallic material with a high degree of strength.
In techniques proposed in the related art, as described in Japanese Unexamined Utility Model (Registration) Application Publication (JP-UM-A) Nos. S63-178126 and S61-009135, and Japanese Unexamined Patent Application Publication No. 2001-032819, the fiber reinforced plastic is adhered directly to the metallic material, thereby eliminating the need for a fastening tool, and as a result, a reduction in weight and so on are achieved.
In the case where two members are joined by adhesion, if end surfaces of the two members are mated such that a resulting mating surface serves alone as an adhesion surface, the adhesion surface is small, and therefore a large degree of strength cannot be expected from a resulting joint structure.
A joint structure described in JP-UM-A No. S63-178126 employs a step-shaped joint surface obtained by forming complementary step structures on each of the end portions of two members to be joined. As a result, an adhesion surface having a large surface area is secured on a step surface that is perpendicular to the mating surface.
A joint structure described in JP-UM-A No. S61-009135 employs a multi-step-shaped joint surface in a tube material. Further, JP-UM-A No. S61-009135 describes a structure in which the step-shaped joint surfaces are superposed in two layers (see FIG. 3 of JP-UM-A No. 061-009135). In this structure, an end portion of a metallic material formed in a tapered step shape is inserted into a groove formed in a shallow step shape that opens onto an end surface of a fiber reinforced plastic.
In a joint structure described in JJP-A No. 2001-032819, a fiber reinforced plastic and a metallic material are disposed so as to overlap partially and wound together in a shaft material with axial direction ends thereof arranged diagonally. Thus, the two materials are superposed alternately in a plurality of layers on a cross-section passing through an axis thereof.
According to the technique described in JP-A No. 2001-032819, however, although the two materials can be superposed alternately to form a multi-layer structure, it is only possible to form a roll-shaped pipe material, and a planar structure or a structure having a desired curve cannot be formed. Moreover, a step-shaped joint surface, and in particular a multi-step step-shaped joint surface, cannot be formed. Furthermore, as the two materials are wound, a region in which the materials are superposed gradually becomes misaligned in the axial direction such that the region increases in length. It is difficult to form another structure simultaneously in a structural portion used as a joint. Therefore, when the joint structure increases in size, a degree of design freedom is restricted correspondingly. As a result, application locations for the joint structure become limited, which is undesirable.
Furthermore, the technique described in JP-UM-A No. 163-178126 relates to a joint structure formed by superposing a single layer of fiber reinforced plastic and a single layer of metallic material. In the technique described in J JP-UM-A No. S61-009135, the metallic material is not provided in more than two layers.
Hence, with the conventional techniques described above, it is difficult to obtain a structure that is formed by alternately superposing at least two layers each of a fiber reinforced plastic and a metallic material and has a planar shape or a desired curved shape. Moreover, limitations occur naturally in a layer thickness of the layers relative to an overall required thickness, making it difficult to increase the number of layers.